Cryptography – Video cryptography – Video electric signal masking
Patent
1997-09-12
2000-08-15
Hayes, Gail O.
Cryptography
Video cryptography
Video electric signal masking
H04N 7167
Patent
active
061048143
ABSTRACT:
In a system for jamming television programs in a cable television system, modified oscillators are used to provide jamming signals to control ports where they are added to the video signal, in order to prevent unauthorized viewing. The oscillators have switchable portions so that they, when receiving appropriate control signals from a control unit on control lines, can be switched to different basic oscillation frequencies and thus each one can cover a very wide frequency range. The basic oscillation frequency of the oscillators is finely adjusted by means of a continuous signal on a line like the conventional voltage control of oscillators. The use of such switched oscillators in an interdiction apparatus for a cable television system provides a number of advantages, such as making the system more flexible and more efficient in terms of jamming capacity for more expensive programs, pay channels, needed oscillator circuitry, etc.
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Bladh Mats
Soderqvist Rickard
Hayes Gail O.
Seal James
Telefonaktiebolaget LM Ericsson
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